所以我正在尝试创建一个方法，允许我输入一个轨道ID，然后返回属于轨道ID的轨道名称。
我需要使用XPath将XML文档解析为java，然后将序列化新库。我的XML文档示例如下：
<plist version="1.0">
<dict>
<key>Major Version</key>
<integer>1</integer>
<key>Minor Version</key>
<integer>1</integer>
<key>Date</key>
<date>2015-03-16T15:04:23Z</date>
<key>Application Version</key>
<string>12.1.0.71</string>
<key>Features</key>
<integer>5</integer>
<key>Show Content Ratings</key>
<true/>
<key>Music Folder</key>
<string>
file://localhost/C:/Users/Mark/Music/iTunes/iTunes%20Media/
</string>
<key>Library Persistent ID</key>
<string>3B01AE08EA513C21</string>
<key>Tracks</key>
<dict>
<key>646</key>
<dict>
<key>Track ID</key>
<integer>646</integer>
<key>Name</key>
<string>Save Me</string>
<key>Artist</key>
<string>Avenged Sevenfold</string>
<key>Album Artist</key>
<string>Avenged Sevenfold</string>
<key>Album</key>
<string>Nightmare</string>
<key>Genre</key>
<string>Metal</string>
<key>Kind</key>
<string>MPEG audio file</string>
<key>Size</key>
<integer>23257166</integer>
<key>Total Time</key>
<integer>656535</integer>
<key>Disc Number</key>
<integer>1</integer>
<key>Disc Count</key>
<integer>1</integer>
<key>Track Number</key>
<integer>11</integer>
<key>Track Count</key>
<integer>11</integer>
<key>Year</key>
<integer>2010</integer>
<key>Date Modified</key>
<date>2012-10-21T22:07:20Z</date>
<key>Date Added</key>
<date>2012-10-21T22:07:20Z</date>
<key>Bit Rate</key>
<integer>276</integer>
<key>Sample Rate</key>
<integer>44100</integer>
<key>Play Count</key>
<integer>2</integer>
<key>Play Date</key>
<integer>3415934327</integer>
<key>Play Date UTC</key>
<date>2012-03-30T06:38:47Z</date>
<key>Artwork Count</key>
<integer>1</integer>
<key>Persistent ID</key>
<string>0000000000001389</string>
<key>Track Type</key>
<string>File</string>
<key>Location</key>
<string>
file://localhost/C:/Users/Mark/Music/Avenged%20Sevenfold/Nightmare/11%20-%20Save%20Me.mp3
</string>
<key>File Folder Count</key>
<integer>2</integer>
<key>Library Folder Count</key>
<integer>1</integer>
</dict>
<key>648</key>
<dict>
<key>Track ID</key>
<integer>648</integer>
<key>Name</key>
<string>Welcome 2 Hell</string>
<key>Artist</key>
<string>Bad Meets Evil</string>
<key>Album Artist</key>
<string>Bad Meets Evil</string>
<key>Composer</key>
<string>Havoc, Magnedo7</string>
<key>Album</key>
<string>Hell: The Sequel (Deluxe Edition)</string>
<key>Genre</key>
<string>Rap</string>
<key>Kind</key>
<string>MPEG audio file</string>
<key>Size</key>
<integer>7467977</integer>
<key>Total Time</key>
<integer>177606</integer>
<key>Track Number</key>
<integer>1</integer>
<key>Year</key>
<integer>2011</integer>
<key>Date Modified</key>
<date>2012-10-21T22:07:20Z</date>
<key>Date Added</key>
<date>2012-10-21T22:07:20Z</date>
<key>Bit Rate</key>
<integer>320</integer>
<key>Sample Rate</key>
<integer>44100</integer>
<key>Play Count</key>
<integer>3</integer>
<key>Play Date</key>
<integer>3424485861</integer>
<key>Play Date UTC</key>
<date>2012-07-07T06:04:21Z</date>
<key>Skip Count</key>
<integer>2</integer>
<key>Skip Date</key>
<date>2012-11-26T14:02:44Z</date>
<key>Artwork Count</key>
<integer>1</integer>
<key>Persistent ID</key>
<string>000000000000138A</string>
<key>Track Type</key>
<string>File</string>
<key>Location</key>
<string>
file://localhost/C:/Users/Mark/Music/Bad%20Meets%20Evil/Hell_%20The%20Sequel%20(Deluxe%20Edition)/01%20-%20Welcome%202%20Hell.mp3
</string>
<key>File Folder Count</key>
<integer>2</integer>
<key>Library Folder Count</key>
<integer>1</integer>
</dict>
</plist>
现在，我对XPath和XML一般都很陌生，并且由于它的复杂性和庞大的规模，我正在努力浏览iTunes XML文件。
到目前为止，我的想法是导航到<key>646</key>以检查ID，然后使用<string>Save Me</string>导航到曲目名称"//dict/key[.="646"]/string[1]/text()"。
这会产生NULL。到目前为止，我用Java编写的代码是：
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpression;
import javax.xml.xpath.XPathExpressionException;
import javax.xml.xpath.XPathFactory;
import org.w3c.dom.Document;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;
public class XMLparse {
public XMLparse(){
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
factory.setNamespaceAware(true);
DocumentBuilder builder;
Document doc = null;
try {
builder = factory.newDocumentBuilder();
doc = builder.parse(new File("C:\\musicLibrary.xml"));
// Create XPathFactory object
XPathFactory xpathFactory = XPathFactory.newInstance();
// Create XPath object
XPath xpath = xpathFactory.newXPath();
int id = 646;
String name = getTrackNameById(doc, xpath, id);
System.out.println("Track Name with ID " + id + ": " + name);
} catch (ParserConfigurationException | SAXException | IOException e) {
e.printStackTrace();
}
}
public static String getTrackNameById(Document doc, XPath xpath, int id) {
String name = null;
try {
XPathExpression expr = xpath.compile("//dict/integer[.="+id+"]/string[1]/text()");
name = (String) expr.evaluate(doc, XPathConstants.STRING);
} catch (XPathExpressionException e) {
e.printStackTrace();
}
return name;
}
}
非常感谢任何帮助。
编辑：
使用MathiasMüller的建议按预期为轨道646产生了正确的结果“Save Me”。但是，当我输入另一个曲目ID时，它也会返回“Save Me”，这是不正确的。
我不知道为什么会这样做，因为我认为它只会返回我输入的ID的曲目名称，但它会返回不同的曲目名称？
第二次编辑：
- 包含更多XML
第三次编辑：
使用Mathias的建议将XPath表达式更改为//dict[integer ="+id+"]/string[1]/text()。这很完美。
答案 0 :(得分：1)
我无法评论Java代码，但我可以向您解释您应该使用的XPath表达式。假设您已显示的输入样本，请应用
//dict[key='646']/dict/key[. = 'Name']/following-sibling::*[1]
将返回
<string>Save Me</string>
这是你要找的元素。要仅选择其文本内容，请使用
//dict[key='646']/dict/key[. = 'Name']/following-sibling::*[1]/text()
，结果将是
Save Me
路径表达式的工作原理如下：
//dict select `dict` elements anywhere in the document
[key='646'] but only if they have an immediate child `key` whose text
content is equal to "646"
/dict select their child elements called `dict`
/key[. = 'Name'] of those `dict` elements select their child elements `key`,
but only if their text content is equal to "Name"
/following-sibling::*[1] of those `key` elements, select the first following sibling
element
/text() and select its text content
原始表达式依赖于string元素的位置，也可以进行微小的更改：
//dict[key ="646"]/dict/string[1]/text()